The present invention relates generally to continuously supplying flexible raw material generally in the form of a web to a processing machine, and more particularly to a stock of ribbon material and methods for controlling twisting of the ribbon material fed to the processing machine.
Conventional processing machines, such as those used to convert narrow ribbons of raw material into finished product, run most efficiently when a continuous feed of raw material is provided. If continuous feed of raw material is not maintained, the machine must be shut down to re-thread the ribbon material. Shutting down the machine negatively impacts the efficiency of the machine, especially machines used in high volume processes such as the production of feminine care products.
Raw absorbent material used to produce feminine care products is initially manufactured as a web of absorbent material measuring one meter or more in width. The processing machine cannot process such a wide web, so the material is trimmed to form many ribbons of a more usable narrow width. The wide web is suitably scored or sheared to form the ribbons. Typically, the ribbons are then wound onto cores to form coils or xe2x80x9cpancake slitsxe2x80x9d, so-called due to the fact they resemble pancakes when laid flat. Each coil has a thickness substantially equal to a width of the ribbon material, and each successive revolution or turn of ribbon substantially overlies the preceding revolution so that the coil is no thicker than the ribbon material is wide.
The coils are shipped to a factory where the processing machine is located, and one coil at a time is mounted on a horizontal axis spindle for continuous feed of raw material into the processing machine. The machine pulls the ribbon in a direction tangential to the coil, i.e., parallel to a plane of the coil and perpendicular to an axis of the coil, so that there is no twisting of the ribbon during feeding. The spindle is a variable-speed motorized spindle with sufficient capacity for mounting only one coil of absorbent material. The spindle is variable-speed to keep tension in the ribbon as it is fed into the machine. It will be understood that at a constant linear feed rate, the coil will rotate faster as its supply of ribbon is consumed by the machine. Due to the high cost of each spindle, no more than two spindles are typically provided at the machine. Thus, as a first coil is consumed, a second coil is mounted on the second spindle, and the trailing end of the first coil is spliced to a leading end of the second coil.
An obvious disadvantage of this arrangement is that an operator must be standing by to load coils as they are consumed by the machine. The time period between changing coils (referred to as runout time) will vary with the length of the material on the coil and the speed of use by the processing machine. In the case of a relatively high throughput feminine pad machine, a typical one thousand lineal meter coil of absorbent material will be consumed in three to nine minutes. Due to this relatively short runout time, the processing machine requires constant manpower to maintain continuous feed. Moreover, the short runout time and the difficulty of loading the bulky coil on the spindle increases the likelihood that the splice will fail (e.g., due to operator error or mechanical problems in splicing) and the likelihood that the machine will have to be shutdown for re-threading.
There are other methods of providing continuous feed material to a processing machine. For example a processing machine is shown in U.S. Pat. No. 1,178,566 (Wright) wherein the ribbon material is formed into a stack of coils, and an end of the upper coil is pulled parallel to the axis of the coil into the machine. This arrangement causes the ribbon material to twist as it is unwound. The patent shows a device for removing the twists including a rotatable guide which rotates in response to twists in the ribbon and a powered turntable which intermittently rotates the coils (i.e., rotation starts and stops repeatedly) in response to rotation of the guide.
Briefly, apparatus of this invention is a twist controlling device for ribbon material wound in a coil about a central axis. The device controls twists in the ribbon material as it is fed from the coil to a processing machine. The device includes a gate adapted to be positioned along a ribbon feed path from the coil to the processing machine and having an opening therethrough for receiving the ribbon material. The gate is adapted to engage the ribbon and is rotatable about a gate axis generally coincident with a center of the opening for controlling twisting of the ribbon.
In another aspect of the invention, a device for receiving and selectively orienting material includes a bearing assembly including an outer ring and an inner ring rotatably mounted inside the outer ring for rotation about a central gate axis. First and second rollers are rotatably mounted inside the inner ring for rotation about roller axes transverse to the gate axis. The rollers are mounted in parallel spaced relation for receiving the material therebetween. The rollers are adapted to engage the material to control the material orientation by rotation of the inner ring.
In yet another aspect, the present invention provides an axial feed system of a processing machine for continuously feeding a coil of ribbon material thereto. The coil has a central axis perpendicular to a plane of the coil. The system includes an intake feed mechanism for pulling the ribbon material into the processing machine. The intake feed mechanism is adapted to pull the ribbon material from the coil in a twist-promoting direction. The intake feed mechanism includes a plurality of gates adapted for controlling twists in unwound ribbon material. Each gate includes an opening therethrough for receiving the ribbon material therethrough and is rotatable about a gate axis generally coincident with a center of the opening for controlling the twists.
Other features of the present invention will be in part apparent and in part pointed out hereinafter.